Adds support for continuing to track tables across function calls

docsrc/warnings.rst

@@ -31,7 +31,9 @@ Code Description
 312  Value of an argument is unused.
 313  Value of a loop variable is unused.
 314  Value of a field in a table literal is unused.
+315  Unused table field
 321  Accessing uninitialized local variable.
+325  Accessing unitialized table field
 331  Value assigned to a local variable is mutated but never accessed.
 341  Mutating uninitialized local variable.
 411  Redefining a local variable.

luacheck-dev-1.rockspec

@@ -50,6 +50,7 @@ build = {
       ["luacheck.stages.detect_empty_blocks"] = "src/luacheck/stages/detect_empty_blocks.lua",
       ["luacheck.stages.detect_empty_statements"] = "src/luacheck/stages/detect_empty_statements.lua",
       ["luacheck.stages.detect_globals"] = "src/luacheck/stages/detect_globals.lua",
+      ["luacheck.stages.check_table_fields"] = "src/luacheck/stages/check_table_fields.lua",
       ["luacheck.stages.detect_reversed_fornum_loops"] = "src/luacheck/stages/detect_reversed_fornum_loops.lua",
       ["luacheck.stages.detect_unbalanced_assignments"] = "src/luacheck/stages/detect_unbalanced_assignments.lua",
       ["luacheck.stages.detect_uninit_accesses"] = "src/luacheck/stages/detect_uninit_accesses.lua",

spec/cli_spec.lua

@@ -738,18 +738,19 @@ Total: 8 warnings / 3 errors in 2 files
 
    it("shows correct ranges for files with utf8", function()
       assert.equal([[
-Checking spec/samples/utf8.lua                    4 warnings
+Checking spec/samples/utf8.lua                    5 warnings
 
     spec/samples/utf8.lua:2:1-4: setting undefined field '분야 명' of global 'math'
     spec/samples/utf8.lua:2:16-19: accessing undefined field '値' of global 'math'
     spec/samples/utf8.lua:3:25-25: unused variable 't'
     spec/samples/utf8.lua:4:5-28: value assigned to field 'päällekkäinen nimi a\u{200B}b' is overwritten on line 5 before use
+    spec/samples/utf8.lua:5:5-28: value assigned to table field 't'.'päällekkäinen nimi a​b' is unused
 
 Checking spec/samples/utf8_error.lua              1 error
 
     spec/samples/utf8_error.lua:2:11-11: expected statement near 'о'
 
-Total: 4 warnings / 1 error in 2 files
+Total: 5 warnings / 1 error in 2 files
 ]], get_output "spec/samples/utf8.lua spec/samples/utf8_error.lua --ranges --no-config")
    end)
 
@@ -1218,10 +1219,10 @@ Checking spec/samples/redefined.lua               7 warnings
 Checking spec/samples/reversed_fornum.lua         1 warning
 Checking spec/samples/unused_code.lua             10 warnings
 Checking spec/samples/unused_secondaries.lua      4 warnings
-Checking spec/samples/utf8.lua                    4 warnings
+Checking spec/samples/utf8.lua                    5 warnings
 Checking spec/samples/utf8_error.lua              1 error
 
-Total: 73 warnings / 5 errors in 19 files
+Total: 74 warnings / 5 errors in 19 files
 ]]):gsub("(spec/samples)/", "%1"..package.config:sub(1, 1)),
             get_output "spec/samples --config=spec/configs/exclude_files_config.luacheckrc -qq --exclude-files spec/samples/global_fields.lua")
          end)
@@ -1243,10 +1244,10 @@ Checking redefined.lua                            7 warnings
 Checking reversed_fornum.lua                      1 warning
 Checking unused_code.lua                          10 warnings
 Checking unused_secondaries.lua                   4 warnings
-Checking utf8.lua                                 4 warnings
+Checking utf8.lua                                 5 warnings
 Checking utf8_error.lua                           1 error
 
-Total: 73 warnings / 5 errors in 19 files
+Total: 74 warnings / 5 errors in 19 files
 ]], get_output(". --config=spec/configs/exclude_files_config.luacheckrc -qq --exclude-files global_fields.lua", "spec/samples/"))
          end)
 
@@ -1265,10 +1266,10 @@ Checking redefined.lua                            7 warnings
 Checking reversed_fornum.lua                      1 warning
 Checking unused_code.lua                          10 warnings
 Checking unused_secondaries.lua                   4 warnings
-Checking utf8.lua                                 4 warnings
+Checking utf8.lua                                 5 warnings
 Checking utf8_error.lua                           1 error
 
-Total: 65 warnings / 5 errors in 17 files
+Total: 66 warnings / 5 errors in 17 files
 ]], get_output(". --config=spec/configs/exclude_files_config.luacheckrc -qq --exclude-files global_fields.lua --exclude-files " .. quote("./read*"), "spec/samples/"))
          end)
 

spec/table_field_limitations_spec.lua

@@ -0,0 +1,141 @@
+local helper = require "spec.helper"
+
+local function assert_warnings(warnings, src)
+   assert.same(warnings, helper.get_stage_warnings("check_table_fields", src))
+end
+
+describe("table field todo tests", function()
+   it("does nothing for globals", function()
+      assert_warnings({}, [[
+x = {}
+x[1] = 1
+x[2] = x.y
+x[1] = 1
+
+y[1] = 1
+y[2] = x.y
+y[1] = 1
+      ]])
+   end)
+
+   it("can't parse complicated values out", function()
+      assert_warnings({}, [[
+local val = nil
+local t = {}
+t[1] = val
+print(t[1])
+      ]])
+   end)
+
+   it("does nothing for nested tables", function()
+      assert_warnings({}, [[
+local x = {}
+x[1] = {}
+x[1][1] = 1
+x[1][1] = x[1][2]
+return x
+      ]])
+   end)
+
+   -- Because of possible multiple return
+   it("assumes tables initialized from functions can have arbitrary keys set", function()
+      assert_warnings({
+         {code = "315", line = 3, column = 3, end_column = 3, name = 'x', field = 'y', set_is_nil = ''},
+      }, [[
+local function func() return 1 end
+local x = {func()}
+x.y = x[2]
+      ]])
+   end)
+
+   it("does nothing for table parameters that aren't declared in scope", function()
+      assert_warnings({}, [[
+function func(x)
+   x[1] = x.z
+   x[1] = 1
+end
+      ]])
+   end)
+
+   it("doesn't handle metatables", function()
+      assert_warnings({}, [[
+local x = setmetatable({}, {})
+x[1] = 1
+print(x[2])
+      ]])
+   end)
+
+   it("detects unused and undefined table fields inside control blocks, but not between them", function()
+      assert_warnings({
+         {line = 4, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+         {line = 10, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+         {line = 16, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+         {line = 22, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+         {line = 28, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+         {line = 34, column = 13, name = 'x', end_column = 13, field = 'z', code = '325', },
+      }, [[
+do
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+end
+
+if true then
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+end
+
+while true do
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+end
+
+repeat
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+until false
+
+for i=1,2 do
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+end
+
+for _,_ in pairs({}) do
+   local x = {}
+   x.y = 1
+   x[1] = x.z
+end
+      ]])
+   end)
+
+   it("halts checking at the end of control flow blocks with jumps", function()
+      assert_warnings({}, [[
+local x = {1}
+if math.rand(0,1) ~= 1 then
+   x = {}
+end
+
+x[1] = x[1]
+
+local y = {1}
+if math.random(0,1) == 1 then
+   y[1] = 2
+else
+   y = {}
+end
+
+y[1] = y[1]
+
+local a = {1}
+while math.random(0,1) == 1 do
+   a = {}
+end
+
+a[1] = a[1]
+      ]])
+   end)
+end)